Apparatus and methods for forming composite stiffeners and reinforcing structures

ABSTRACT

Methods of forming an elongated composite structural member are provided. One method includes, providing a substantially elongated mandrel having an exterior surface exhibiting a desired geometry. Laying up a first ply of preimpregnated fiber reinforced material over the mandrel. Applying a force to the first ply to establish a desired amount of tension within the first ply and then pressing the first ply onto the mandrel in a conformal manner. This includes passing at least one roller over the mandrel and the first ply while maintaining the desired amount of tension within the first ply. The at least one roller is at least partially complementary in shape with the mandrel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 10/903,871 filed onJul. 30, 2004, now U.S. Pat. No. 7,513,769, ('769 Patent) issued Apr. 7,2009. The '769 application is a continuation-in-part of U.S. Pat. No.7,249,943 ('943 Patent), filed Aug. 1, 2003. Both the '769 Patent andthe '943 patent are assigned to the Assignee hereof, the disclosure ofboth are incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the formation of compositestructures and, more particularly, to the formation of the stiffeners orother reinforcing members associated with such composite structuresincluding reinforcing members exhibiting arcuate or curved elongatedgeometries.

2. State of the Art

In the fabrication of composite structures, structural members are oftenattached to a skin to provide reinforcement of the skin. Such structuralmembers may include, for example, ribs, spars or frames configured to beattached to the skin of the composite structures. Such structuralmembers may also include substantially elongated stiffening membersoften referred to as stringers or stiffeners. The stringers orstiffeners may be formed to exhibit various cross-sectional geometriesincluding configurations such as I-beams, C-shapes (sometimes referredto as U-shapes or channels), J-shapes, Z-shapes, L-shapes or angles,omega shapes or what is often referred to as a hat shape or a hatchannel. A stiffener or stringer exhibiting a cross-sectional geometryor profile of a hat essentially includes a cap member having a pair ofweb members, one web member extending from each end of the cap member ata defined angle relative thereto, and a pair of flange members with oneflange member extending from each web member at a defined angle relativeto the associated web member. In the cross-sectional geometry of somehat stiffeners, the flange members may be configured to be substantiallyparallel with the cap member.

A current method of forming composite hat stiffeners, as well asstiffeners exhibiting other cross-sectional geometries, includes layingup composite plies by hand, one at a time, over a mold, mandrel or othersimilar tool to form a laminate structure. Upon laying up every two tothree plies, the laminate structure needs to be compacted or debulked.This is conventionally accomplished by vacuum debulking wherein a vacuumbag is placed over the laminate structure and a vacuum applied to thestructure by way of the bag. Often, heat may be applied to assist in thedebulking process and in an attempt to further compact the laminatestructure. Each vacuum debulk performed on the laminate structurerepresents a time consuming process. In forming the laminate structure,multiple vacuum compactions may need to take place upon the building upof layers to form the laminate structure. However, even with multiplevacuum debulks being performed on a given laminate structure, thelaminate structure may still undesirably exhibit a significant amount ofbulk.

Once all of the plies have been positioned and the laminate structurehas been initially formed (including the process of subjecting thelaminate structure to vacuum debulking processes), the laminatestructure may be cured and subsequently attached to a skin structure,such as with adhesive, or it may be cocured (cured concurrently) withthe skin structure thereby bonding the two components together. Curingof the laminate structure is conventionally accomplished by placing thelaminate structure in a cure mold and subjecting it to a high pressureand high temperature such as in an autoclave or similar environment.

When the laminate structures are placed in a cure mold, because theystill exhibit a substantial amount of bulk, they sometimes do not fitproperly within the mold. Furthermore, while any remaining bulkexhibited by the laminate structure tends to be driven out during thecuring process, such as in an autoclave, there is little, if any, slipallowed between the plies of the laminate structure and, as a result,ply bridging and ply wrinkling will often occur within the cured orpartially cured laminate structure.

While it is possible to obtain structures with low bulk characteristicsby subjecting the structures to multiple hot debulks under autoclavepressure, such is a very time consuming and expensive process.Additionally, such a process may shorten the working life of thelaminate structure due to the repeated subjection thereof to hightemperatures. Furthermore, such an aging process can hinder the abilityof the laminate structure to be cocured with a mating skin or otherstructure.

In addition to the issues of obtaining a low bulk structure, theconventional process of forming composite reinforcing structures by handhas other limitations. For example, the method of forming elongatedreinforcing structures by hand poses difficulties in obtaining shapeswhich, besides exhibiting a desired cross-sectional geometry, alsoexhibit bends along a longitudinal axis or twist about the longitudinalaxis of the structure. Such features are difficult to accomplish, inpart, because it is difficult to manipulate the plies by hand to conformto such bends and/or twists without introducing additional wrinkles orwaves into the laminate structure being formed. Furthermore, themanipulation of plies by hand is an extremely time consuming and laborintensive process, thereby increasing the cost of manufacturing suchparts.

Various attempts have been made to provide a process which provideselongated reinforcing structures without the various limitations whichare presented by the conventional process of laying up individualcomposite plies by hand. For example, pultrusion is a process which hasbeen used to form plastic materials, including fiber reinforced plasticcomposite materials, into structures exhibiting a desiredcross-sectional geometry or profile. An example of such a pultrusionprocess is set forth in U.S. Pat. No. 5,026,447 issued to O'Connor.O'Connor teaches the pulling of an elongated body of reinforcedthermoplastic material through a plurality of dies. The dies areoperated independently of each other such that any combination of thedies may be selected to impart a cross-sectional geometry to a portionof the elongated body. The process of O'Connor purportedly allows themanufacture of an elongated thermoplastic member which may exhibitvaried cross-sectional geometries along the length thereof. However, aswill be recognized by those of ordinary skill in the art, there arevarious limitations associated with the process of pultrusion.

For example, pultrusion is conventionally associated with materialsutilizing a thermoplastic resin. The use of thermosetting resins maycause a build up of material on the dies and cause considerableinefficiencies in forming the desired cross-sectional shape of thepultruded member. Additionally, it is often difficult to obtain a fiberorientation in the resultant member which varies significantly from thelongitudinal axis of the formed member (i.e., along the direction whichthe member is pulled through the die or dies). Furthermore, because theprocess involves forming the member by pulling a plurality of fibersthrough a die and then cooling the member until the resin substantiallyresolidifies, such a process is generally only effective for formingstraight or linear members of substantially constant cross sections andmay not be effective in forming members exhibiting a substantial changein cross-sectional area or which exhibits substantial non-linearsections along the length thereof. It is also noted that the dies usedin pultrusion are generally expensive to manufacture and that numerousdies are required if it is desired to produce elongated members of morethan one cross-sectional geometry.

Other processes for forming elongated thermoplastic members include, forexample, U.S. Pat. No. 5,891,379 issued to Bhattacharyya et al., andU.S. Pat. No. 5,182,060 issued to Berecz. Bhattacharyya discloses aprocess of forming fiber reinforced plastic material into a desiredshape which includes heating the material to a temperature above themelting temperature of the thermoplastic resin or matrix material. Theheated material is cooled below the melting temperature but stillmaintained at a temperature which is above the recrystallizationtemperature of the thermoplastic material, and then passed through aplurality of roll-forming dies in order to produce a desired shape. Theshaped material is then further cooled so that the fiber reinforcedplastic material will retain the shape imposed thereto by roll-formingdies. Berecz discloses a process of continuously forming a thermoplasticcomposite shape including the heating of unidirectional tape or wovencloth, passing the heated material through a set of rollers, and thenthrough a matched metal die which acts as a rapidly reciprocating punchto form the final shape.

While the processes taught by Bhattacharyya and Berecz appear to allowimproved control of the fiber orientation in the resultant part over aconventional pultrusion process, the disclosed processes appear to belimited to the use of materials comprising thermoplastic resinsincluding subjecting the materials to temperatures at or above meltingtemperatures of the resin prior to forming the desired cross-sectionalgeometries. As will be appreciated by those of ordinary skill in theart, the use of thermoplastic resins provide considerable flexibility inbeing able to melt, or substantially melt, the resin and subsequentlyreheat the resin in order to reshape/rework the member and/or to adherethe member to another structure by means of contacting the otherstructure with the melted or substantially melted resin material.

However, such a process is not amenable to the formation of reinforcingor structural members comprising thermosetting materials since, if thethermosetting resin is heated above a specified temperature to allow theresin to readily flow and thereby assist in forming the compositematerial into a specified cross-sectional geometry, the thermosettingresin will crosslink and cure. Once the reinforcing member is cured, itwill not be possible to perform any subsequent rework of the member. Norwill the member be able to be bonded to another structure throughcocuring.

For example, U.S. Pat. No. 5,043,128 to Umeda discloses a process offorming an elongated composite member utilizing a thermosetting resinwhich includes feeding a plurality of preimpregnated carbon fiber sheetsof material through a pair of shaping rollers and into a heating andpress forming device. The heating and press forming device includes aheating die and a press punch configured to engage the heating die. Thesheets of material are temporarily stopped within the heating and pressforming device and pressed by the punch against the heating die. Thesheets of material are, thus, simultaneously pressed and heatedresulting in the thermosetting, or curing, the sheets of material intothe desired shape. As noted above, a process of forming a structuralmember which includes the curing of a thermosetting resin prevents anysubsequent reworking of the member and/or any cocuring of the structuralmember with, for example, a composite skin or other structural member.Thus, in order to form a structural member exhibiting a desiredcross-sectional geometry from a composite material comprising athermosetting resin which is not fully cured, methods such as thatdescribed above, wherein multiple plies are laid up by hand over amandrel or mold are still utilized.

In view of the shortcomings in the art, it would be advantageous toprovide an apparatus and a method for forming elongated reinforcing orstructural members of a material comprising a thermosetting resin whichenables the member to exhibit a desired cross-sectional geometry withoutfully curing the member.

BRIEF SUMMARY OF THE INVENTION

The above-mentioned problems of current systems are addressed byembodiments of the present invention and will be understood by readingand studying the following specification. The following summary is madeby way of example and not by way of limitation. It is merely provided toaid the reader in understanding some of the aspects of the invention. Inone embodiment, a method of forming an elongated composite structuralmember is provided. The method includes, providing a substantiallyelongated mandrel having an exterior surface exhibiting a desiredgeometry. Laying up a first ply of preimpregnated fiber reinforcedmaterial over the mandrel. Applying a force to the first ply toestablish a desired amount of tension within the first ply and thenpressing the first ply onto the mandrel in a conformal manner. Thisincludes passing at least one roller over the mandrel and the first plywhile maintaining the desired amount of tension within the first ply.The at least one roller is at least partially complementary in shapewith the mandrel.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing and other advantages of the invention will become apparentupon reading the following detailed description and upon reference tothe drawings in which:

FIG. 1 is a perspective view of an apparatus for forming elongatedcomposite members in accordance with an embodiment of the invention;

FIG. 2 is a perspective view of a portion of the apparatus of FIG. 1 inaccordance with an embodiment of the present invention;

FIGS. 3A-3D show partial cross-sectional views of the apparatus of FIG.1 during various stages of forming an elongated member therewith;

FIG. 4 is a perspective view of a portion of the apparatus of FIG. 1 inaccordance with another embodiment of the present invention;

FIG. 5 is a perspective view of another apparatus for forming elongatedcomposite members in accordance with another embodiment of the presentinvention;

FIG. 6 is a perspective view of another apparatus for forming elongatedcomposite members in accordance with yet another embodiment of thepresent invention;

FIG. 7 is an enlarged perspective view of a portion of the apparatusshown in FIG. 6;

FIGS. 8A and 8B show cross-sectional views of elongated reinforcingmembers formed in accordance with various aspects of the presentinvention and at various stages of manufacture;

FIG. 9 is a perspective view of an apparatus for forming elongatedcomposite members in accordance with a further embodiment of the presentinvention;

FIG. 10 is a perspective view of an apparatus for forming elongatedcomposite members in accordance with yet a further embodiment of thepresent invention;

FIG. 11 is a schematic showing the use of a controller with an apparatusfor forming elongated composite members in accordance with an embodimentof the present invention;

FIG. 12A is a perspective view of a mandrel used in forming an elongatedcomposite member in accordance with an embodiment of the presentinvention;

FIG. 12B is a partial cross-sectional side view of the mandrel shown inFIG. 12A during formation of an elongated composite member in accordancewith an embodiment of the present invention; and

FIGS. 13A-13E are cross-sectional views of exemplary geometricconfigurations which may be formed in accordance with the presentinvention;

FIGS. 14A and 14B show a plan view and an elevational view,respectively, of a system and apparatus for forming elongated compositemembers in accordance with yet another embodiment of the presentinvention;

FIG. 15A shows a schematic of an exemplary process carried out by thesystem and apparatus shown in FIGS. 14A and 14B;

FIGS. 15B-15D show details on various components of the apparatus shownin FIGS. 14A, 14B and 15A;

FIGS. 16A and 16B show material dispensing devices which may be used inconjunction with various embodiments of the present invention;

FIGS. 17A and 17B show perspective views of exemplary elongated membersformed using the systems and apparatuses shown and described withrespect to FIGS. 14A, 14B, 16A and 16B;

FIG. 18 shows an enlarged partial plan view of the apparatus shown inFIG. 14A;

FIGS. 19A and 19B show a plan view and an elevational view,respectively, of a system and apparatus for forming elongated compositemembers in accordance with yet a further embodiment of the presentinvention;

FIG. 20 is a cross-sectional view of an elongated member formed inaccordance with a process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, an apparatus 100 is shown for forming elongatedstructural or reinforcing members 102 (referred to herein for simplicityas elongated members), such as stiffeners or stringers, using compositematerials including, for example, carbon fiber reinforced materials andthermosetting resins. The apparatus includes a base 104 having a portionthereof configured as a molding member such as a mandrel 106. A carriageassembly 108, including a frame 110, is movably coupled with the base104 such as, for example, with rollers or slides 112 positioned withincorresponding track members 114. The rollers or slides 112 inconjunction with the track members 114 allow the carriage assembly 108to move along a longitudinally defined axis 115 relative to the base 104in forming the elongated member 102 as shall be described in greaterdetail below herein.

The carriage assembly 108 further includes a rolling member 116, alsoreferred to herein as a roller, configured to be at least partiallycomplementary with, and positioned over, the mandrel 106. The roller 116may be removably coupled with the carriage assembly 108 such that otherrollers may be interchanged therewith at various stages of forming theelongated member 102 or for forming elongated members with differingcross-sectional geometries. The roller 116 may be coupled to thecarriage assembly 108 by way of a suitable bearing member 118 allowingthe roller 116 to turn or roll when engaged with the base 104 and whenthe carriage assembly 108 is moving relative thereto. The roller 116 maybe formed of, or coated with, for example, an elastomer material, suchas, for example, polytetrafluorethylene (PTFE), for purposes ofconforming the roller to the surface of, and more evenly distributingforces over, the laminate materials disposed over the mandrel 106 andwhich are being used to form the elongated member 102 as the roller 116passes thereover.

The frame 110 of the carriage assembly 108 may desirably be configuredsuch that the roller 116 is substantially vertically displaceable oradjustable relative to the base 104. For example, a portion of the frame110, such as a cross-member 120, may be vertically displaceable relativeto the main portion of the frame 110. The carriage assembly 108 is alsoconfigured to exert a generally downward force on the base 104 and,thus, the elongated member 102, by way of the roller 116. Variousmechanisms may be used to exert such a force. For example, asillustrated in FIG. 1, one or more weights 122 may be coupled to thecarriage assembly 108 and, more particularly, to the cross-member 120such that the weights exert a downward force through the roller 116which is coupled with such cross-members 120. In another embodiment, anactuator, such as a hydraulic or pneumatic cylinder, may be coupled tothe frame 110 and configured to exert a substantially downward forceupon the cross-member 120 or some other component such that a pressuremay be applied by the roller 116 to the mandrel 106.

The carriage assembly 108 may also include a heating apparatus 123configured to heat a portion of the elongated member 102 prior to theroller 116 passing thereover. The heating apparatus or device 123 mayinclude, for example, a resistive heater with an associated blower, aninfrared heater, an ultrasonic heating device, a laser heating device,an electron beam heater or another appropriate heating device. In oneembodiment, the heating device 123 may be configured and located to heatthe mandrel 106, the roller 116 or both. In another embodiment, theheating device 123 may be configured and oriented to heat a portion ofthe elongated member 102 and, more particularly, a portion of one ormore composite material sheets laid down on the mandrel 106 to form theresulting elongated member 102 as shall be discussed in greater detailbelow. Such a heating device 123 may be particularly useful in formingelongated members from preimpregnated or “prepreg” materials. Suchprepreg materials may include unidirectional tape or cloth materialimpregnated with a resin in a B-stage form (uncured). The application ofheat to such prepreg materials may enable the material sheets to morereadily conform to the shape of the mandrel 106 and, more importantly,helps to effect consolidation of the laminar structure, includingmultiple overlaying sheets of material, as such a structure is formed onthe mandrel 106.

It is noted that the application of heat could be used to cure theelongated member 102 upon formation thereof (sometimes termed as“cure-on-the-fly”). However, the present invention also contemplates theability to form an elongated member 102 which is substantially uncured.In other words, the present invention includes forming elongated memberswhich are not significantly cured beyond the B-stage of a conventionalprepreg material (also sometimes referred to as forming “green”structures or members). The ability to form uncured components providesfor substantial flexibility in forming and manufacturing a compositestructure including the ability to cocure the elongated members with acorresponding composite skin as is often desirable.

A cooling device 124 may also be coupled to the carriage assembly 108 tocool the elongated member 102, the roller 116, or some other tool orcomponent associated with the apparatus 100. The cooling device 124 mayinclude, for example, a vortex cooler, a system for circulating acooling fluid through an interior portion of the roller 116, a cryogeniccooler, or a multiple phase system utilizing a condenser and evaporator.

Referring now to FIG. 2 and FIGS. 3A-3D in conjunction with FIG. 1, theformation of an elongated member 102 is illustrated. In FIG. 2, the base104 and mandrel 106 are shown without the carriage assembly 108 forpurposes of clarity and convenience. FIG. 2 also shows a plurality ofrollers 116A-116D engaging the elongated member 102 and associatedmandrel 106 in at least a partially complementary manner. It is notedthat if the particular apparatus 100 shown and described with respect toFIG. 1 is used, each roller 116A-116D may be individually andselectively coupled with the carriage assembly 108 and engaged with theelongated member 102 and mandrel 106. In other words, a first roller116A may first be utilized with the carriage assembly 108 and thenremoved and replaced with a second roller 116B. The rollers 116A-116Dmay be sequentially and progressively interchanged to effectintermediate steps of formation on the elongated member 102.

For example, in forming an elongated member 102, plies of material(e.g., prepreg material) may be positioned on the mandrel 106, and uponone another, in a laminar manner. The first roller 116A may then becoupled to the carriage assembly 108, configured to engage the mandrel106 and rolled along the base 104 to form an intermediate structure102A, or a structure exhibiting an intermediate cross-sectional geometrytaken substantially transverse to the length thereof, such as shown inFIG. 3A. The first roller 116A may then be removed from the carriageassembly 108 and the second roller 116B may be coupled therewith. Thesecond roller 116A engages the mandrel 106 and, as the carriage assembly108 moves relative to the base 104, applies a rolling pressure to thefirst intermediate structure 102A to effect the formation of a secondintermediate structure 102B such as shown in FIG. 3B. Similarly, thethird roller 116C may be used to form a third intermediate structure102C and the fourth roller 116D may be used to form the final structure102D, or the structure exhibiting the final desired cross-sectionalgeometry as taken substantially transverse to the length of theelongated member 102.

In one embodiment, the formation of the elongated member 102 may beconducted on a ply-by-ply basis. In other words, formation of theelongated member 102 may be effected by shaping a first ply to thedesired cross-sectional geometry (e.g., by applying the ply to themandrel 106 and passing the rollers 116A-116D thereover), applying asecond ply of material and shaping the second ply of material to thedesired cross-sectional geometry and conformally with the first shapedply. The act of shaping the second or any subsequent ply through use ofthe rollers 116A-116D also serves to consolidate the plies and debulkthe elongated member 102. Thus, the shaping and debulking of theelongated structure occurs as a substantially continuous andinterrelated process.

In another embodiment, multiple plies may be placed over the mandrel 106and shaped to a desired cross-sectional geometry simultaneously whilealso being consolidated and debulked. Thus, for example, two or threeplies of material may be placed on the mandrel 106 and shaped andconsolidated by the rollers 116A-116D followed by placement of two orthree more plies of material over the shaped plies and the subsequentshaping thereof by the rollers 116A-116D.

The use of multiple rollers 116A-116D in sequentially formingintermediate structures 102A-102C and, ultimately, the final structure102D, enables manipulation of the material (e.g., the prepreg plies)while imposing a relatively reduced amount of stress thereto than if theelongated member was formed in a single operation or a single pass of anindividual roller. Perhaps more importantly, the multiple layers of, forexample, prepreg material used to form the elongated member becomesubstantially consolidated and debulked during the formation of theintermediate structures 102A-102C.

It is noted that more or fewer rollers may be used in forming theelongated members depending, for example, on the type of material beingused, the number of plies or layers of material being utilized to formthe elongated member 102, the number of plies being shaped during agiven operation, and/or the desired cross sectional shape of theresulting elongated member 102. Similarly, the incremental change inroller size may be adjusted depending on similar parameters.

It is also noted that, in forming intermediate structures, the rollers116A-116D are progressive in their respective geometries. In otherwords, the first roller 116A only partially engages the mandrel andmaterial laid thereover in that the outer sections 125A only extendpartially down the side walls 127 of the complementary mandrel 106. Thesecond roller 116B, while still only partially engaging the mandrel 106,does so more than did the first roller 116A. Similarly, the third roller116C is configured to more fully engage the mandrel 106 than does thesecond roller 116B. Finally, the fourth roller 116D is configured tosubstantially fully engage the mandrel 106 such that its outer sections125D extend fully down the side walls 127 of the mandrel 106.

The embodiment shown and described with respect to FIGS. 1, 2 and 3A-3Cinclude a male mandrel 106 and rollers 116A-116D that exhibit acomplementary female geometry. However, in another embodiment, such asshown in FIG. 4, a female mandrel 106′ may be utilized with a pluralityof complementary male rollers 116A′-116D′ wherein the rollers116A′-116D′ press the composite material into the female mandrel 106′ toform the elongated member 102. As with the previously describedembodiment, the rollers 116A′-116C′ may be sequentially andprogressively used to form intermediate structures with the fourth orlast roller 116D′ being used to impose the final cross-sectionalgeometry to the elongated member 102 (or to individual plies of theelongated member, as discussed hereinabove). One or more of the rollers116A′-116D′ may include laterally extended, reduced diameter sections126 to help form the upper corners 128 and the flags 130 or laterallyextending portions of the elongated member 102.

Referring now to FIG. 5, an apparatus 200 for forming an elongatedmember 202 is shown in accordance with another embodiment of the presentinvention. The apparatus includes a movable base 204 having a pluralityof mandrels 206A-206C. A carriage assembly 208 is movably coupled with astationary gantry 210. The carriage assembly 208 is configured tohorizontally travel along the gantry 210 as indicated by directionalarrow 211. The base 204 is also configured to travel along tracks 214relative to both the gantry 210 and the carriage assembly 208. The base204 may be motivated along the tracks 214 by an appropriate drivemechanism 215 such as a motor and gear box. The movement of the base 204along the tracks 214 enables various tools (i.e., bases of otherconfigurations) to be introduced beneath the gantry 210 from either endthereof.

A roller 216, configured to complementarily engage one or more of themandrels 206A-206C, may be removably coupled to the carriage assembly208 and may be coupled to an actuator 217 such that the roller 216 maybe moved in the substantially vertical direction as indicated bydirectional arrow 218. The roller 216 may also be configured to swivelor rotate about a substantially vertical axis as indicated bydirectional arrow 219. The rotation of the roller 216 about thesubstantially vertical axis may be accomplished, for example, byallowing the roller to freely swivel such that it generally follows themandrel (e.g., 206B) with which it is engaged as the carriage assembly208 moves in the direction of directional arrow 211. In anotherembodiment, an actuator 217 may be used to motivate the roller 216 aboutthe substantially vertical axis as may be desired.

A drive mechanism 220 may be configured to move the roller 216 and itsassociated actuator 217 laterally with respect to the base 204 and thegantry 210 as indicated by directional arrow 222. The ability to controlthe movement of the carriage assembly 208 relative to the base 204allows considerable flexibility in forming elongated members 202. Forexample, the same roller 216 may be used to selectively andindependently engage each of the plurality of mandrels 206A-206B.

Additionally, the elongated members 202 may be formed as relativelycomplex shapes, not only with respect to their cross-sectionalgeometries, but also with respect to their geometries along a definedlongitudinal axis. For example, the base 204 of the presently describedapparatus 200 includes a first relatively flat section 224, a slopedsection 226, and a second relatively flat section 228 with the slopedsection 226 being connected to adjacent flat sections 224 and 228 bycurved transition sections 230 and 232. The mandrels 206A-206C generallycomply with the contour or geometry of the base 204. Thus, as thecarriage assembly 208 travels longitudinally as indicated by directionalarrow 211, the roller 216 must be vertically displaced as indicated bydirectional arrow 218 in order to remain engaged with a correspondingmandrel (e.g., 206B).

In other embodiments, the mandrels 206A-206C may deviate laterallyrelative to the longitudinal direction of the base 204 (i.e., in thedirection indicated by directional arrow 222). Such complex geometriesmay be accommodated by the present invention through the various degreesof freedom offered by the arrangement shown. It is noted that, in oneembodiment, the roller 216 may be coupled to a wrist 234 which allowsthe axis upon which the roller 216 rotates to be varied. Thus, theroller 216 may be able to remain in substantial contact with a mandrel(e.g., 206B) even if the mandrel 206B exhibits a twist or rotationrelative about its longitudinal axis and, thereby, enable the formationof elongated members 202 exhibiting a similar twist relative to theirrespective longitudinal axes.

In forming elongated members 202 with the above described apparatus 200,the roller 216 may be operated in a manner similar to that describedabove with respect to FIGS. 1, 2, 3A-3C and 4. In other words,intermediate structures may be formed by using a plurality of stagedrollers (e.g., rollers which progressively change in shape toprogressively engage the associated mandrels 206A-206C). Additionally,the mandrels 206A-206C may be either male or female components and thecorresponding rollers 216 formed to complement such mandrels asnecessary or desired. Also, the elongated member 202 may be formed byshaping individual plies one at a time, or by shaping a plurality ofplies simultaneously.

Referring now to FIG. 6, an apparatus 300 for forming elongated members302 is shown in accordance with another embodiment of the presentinvention. The apparatus includes a base 304 having a plurality ofmandrels 306A-306D mounted or located thereon. A positionable gantry 310(or carriage assembly) is movably coupled with the base 304 andconfigured to move, for example, in a longitudinal direction asindicated by directional arrow 311 relative to the base 304. Associatedwith each mandrel 306A-306D is a device 312A-312D for laying up andforming a plurality of plies of composite material thereon. The devices312A-312D may each include an automated material dispensing deviceconfigured to dispense, for example, plies of cloth or tape material,and one or more rollers for forming the plies of composite material intoa desired cross-sectional geometry.

Such an automated dispensing device may include cut, clamp and startmechanisms such that individual plies may be dropped and added on thefly as desired or required depending on the configuration of theelongated member 302 being formed. Additionally, an automated dispensingdevice may include a mechanism for maintaining tension on the ply ofmaterial as it is being dispensed on to a mandrel 306A-306D. Applicationof tension to the material ply may be desirable to keep any wrinklesfrom developing in the material as the elongated members 302 are beingformed. In one exemplary embodiment, a force of approximately 2 to 15pounds-force (lbf) (approximately 8.9 to 66.7 Newtons (N)) may beapplied to material plies as they are disposed on the mandrels306A-306D.

Each device 312A-312D may further include associated actuators or drivemechanisms in order to move the devices 312A-312D relative to the base304 and to apply pressure via an associated roller to any material laidup on the mandrels 306A-306D. Each device 312A-312D may be programmed toform identical stiffeners or form different stiffeners depending on theindividual configuration of the mandrels 306A-306D mounted on the base304.

Referring to FIG. 7, an individual device 312B is shown positioned aboveits corresponding mandrel 306B without the associated gantry 310 (FIG.6) for clarity in describing the operation of the device 312B. Thedevice includes an automated material dispenser 320 including aplurality of ply dispensers 322A-322D for dispensing and laying up pliesof composite material onto the mandrel 306B. It is noted that the plydispensers 322A-322B may be configured to dispense plies of compositematerial, such as prepreg tape or cloth, which vary in width. Using suchvaried width plies of material, the elongated member 302B may beconfigured such that it exhibits a greater thickness (i.e., by inclusionof more plies) in one portion of the elongated member 302B than another.

For example, referring briefly to FIG. 8A in conjunction with FIG. 7,the first ply dispenser 322A may be configured to dispense a ply 330Awhich extends throughout the entire “width” or extent of the elongatedmember's cross-sectional geometry. Another ply dispenser 322C maydispense a ply 330C which only extends across the upper lateral portion332 (e.g., the cap) of the elongated member's cross-sectional geometry.Thus, the elongated member 302B may be designed and tailored withrespect to ply or material placement in accordance with expectedloadings and applied stresses by increasing or reducing the effectivenumber of plies in a given section or portion thereof. Additionally, itis noted that the individual plies of material may be configured toexhibit substantially any desired fiber orientation (or orientations) asmay be needed in accordance with expected loadings and stress states ofthe elongated member 302B. Thus, for example, a first ply may be formedof a material exhibiting a 0° fiber orientation, a second ply mayinclude material exhibiting a 45° fiber orientation and so on. Of courseother fiber orientations and other ply configurations may be used. Theability to selectively orient fibers in such a manner is a significantadvantage over other forming processes, such as pultrusion.

Referring briefly to FIG. 8B in conjunction with FIG. 7, anotherembodiment may include plies 330E-330H which exhibit similar widths toone another but which are staggered or laterally displaced relative toone another. The resulting elongated member 302B′ thus has a step-likeconfiguration on one lateral side thereof and a reversed image of thestep like configuration on the opposing lateral side thereof. Such aconfiguration enables the interlocking of multiple elongated members302B′ in a side-by-side relationship if so desired. The staggered orstep-like configuration may be formed through appropriate control of theply dispensers 322A-322D such as, for example, by laterally displacingone ply dispenser (e.g., 322A) relative to another (e.g., 322B).

In another embodiment, one or more edge ply cutting devices 341 may beutilized to trim the edge (or edges) of any ply 330A-330H (FIGS. 8A and8B) dispensed over an associated mandrel 306A-306C. Such a cuttingdevice 341 may include a knife, a rolling blade, a laser, or otherappropriate cutting means configured to trim the edge of a ply 330A at adesired width or lateral position as the gantry 310 (not shown in FIG.7) moves longitudinally relative to a mandrel 306A-306C.

Still referring to FIG. 7, the individual device 312B also includes aforming device 340. The forming device 340 may include a plurality ofrollers 342 configured to at least partially complementarily engage withthe mandrel 306B and thereby sequentially form, in a substantiallycontinuous manner, the desired cross-sectional geometry of the elongatedmember 302B. The rollers 342 may be individually coupled to one of aplurality of actuators 344 such as, for example, hydraulic or pneumaticcylinders, so that pressure may be applied through the rollers as theypass over the plurality of plies of material laid upon the mandrel 306B.Thus, rather than interchanging rollers which pass over an associatedmandrel in individual passes, such as described above with respect toother embodiments, the plurality of rollers 342 may be combined in asingle unit to immediately follow one another along the mandrel 306Bduring a single pass to form the desired cross-sectional geometry of theelongated member 302 or of one or more plies thereof.

Referring now to FIG. 9, an apparatus 400 for forming elongated members402 is shown in accordance with yet another embodiment of the presentinvention. While not shown for purposes of convenience and clarity, theapparatus 400 may include various components, such as described above,including a base, a gantry, and/or a carriage assembly which arerelatively movable with respect to each other. The apparatus may alsoinclude, for example, an automated material dispensing device for layinga plurality of plies of composite material onto the mandrel 404.

The apparatus 400 includes a plurality of rollers 406 (individuallyidentified as rollers 406A-406E) which are each configured to engage aspecific portion of the mandrel 404 (or the material plies layingthereover) in order to form a desired cross-sectional geometry. Forexample, a first roller 406A may be configured to press the plies ofmaterial onto the top surface of the mandrel 404. One set of rollers406B may be configured to form the plies of material about the exteriorcorners of the male mandrel 404. Another set of rollers 406C may beconfigured to press the plies of material against the sides of themandrel 404. A further set of rollers 406D may be configured to pressthe plies of material into the interior corners of the mandrel 404, anda final set of rollers 406E may be configured to press the plies ofmaterial against the laterally extending portions of the mandrel 404.Thus, the plurality of rollers 406 works collectively to substantiallycontinuously form an elongated member 402 of a desired cross-sectionalgeometry over the mandrel 404.

Referring briefly to FIG. 10, another embodiment of the apparatus 400′is shown, similar to that shown and described with respect to FIG. 9,except that the mandrel 404′ is configured as a female mandrel and therollers 406′ are configured to engage specifically identified portionsthereof in order to form the elongated member 402.

Referring briefly to FIG. 11, any of the above apparatuses may beoperatively coupled with a controller 500 which may include, forexample, a computer having a processor 502, a memory device 504, one ormore input devices 506 and one or more output devices 508. Such acontroller may be programmed to control the associated apparatus 100,200, 300 and 400 such as, for example, using computer number control(CNC) programming. The controller 500 may be configured to control therelative positions of, for example, the base, the carriage assembly, thegantry, and the roller devices of the various apparatuses set forthherein including what may be termed the vertical, yaw, roll, and pitchpositions and orientations of the rollers of a given apparatus. Thecontroller 500 may be configured to not only control the verticalposition of the roller relative to the mandrel that the roller isintended to engage, but also the amount of pressure or force applied bythe roller to the mandrel or the one or more plies of material laidthereover. Furthermore, the controller 500 may be configured to controlthe amount of heat being applied to the mandrel or associated plies ofmaterial, the position of the material relative to a mandrel, and theclamping, cutting and starting of material being fed from an automatedmaterial dispenser.

While the above described embodiments have largely been discussed usingthe example of individual prepreg materials being laid up on associatedmandrels, it is noted that nonimpregnated fiber materials may beutilized with such materials being laid upon on an associated mandrelwhile substantially simultaneously infusing or impregnating the plies ofmaterial with an appropriate resin or binder. For example, referring nowto FIGS. 12A and 12B, a mandrel 600 may be formed as a perforatedstructure having a plurality of apertures 602 or openings definedtherein. As plies of material 604 are laid over the mandrel 600, one ormore rollers 606 may complementarily engage the mandrel 600 to form theplies into a desired cross-sectional geometry as described above herein.Additionally, one or more spray nozzles 608 or other deposition devicesmay infuse resin or binder into the laid up and formed plies to form ashaped, prepreg structure. The resulting elongated member may bepartially cured or cured to a B-stage such that the elongated member maybe subsequently cocured with an associated composite structure at alater time.

It is noted that the various illustrative embodiments of the inventiondescribed above herein have generally shown an exemplary cross-sectionalgeometry of a hat, or the formation of an elongated member as a hatchannel. However, it is contemplated that the present invention may beused to form elongated members of other cross-sectional geometries. Forexample: at least one C-channel may be formed as illustrated in FIG.13A; at least one structural angle (or similarly a J-shaped or L-shapedcross section) may be formed as illustrated in FIG. 13B; a structuralmember exhibiting at least one arcuate section may be formed asillustrated in FIG. 13C, which may also include flanges to form an omegashape if so desired; a plurality of arcuate cross-sectional shapes maybe formed in a single structural member as shown in FIG. 13D; or aplurality of structural angles may be formed in a single structuralmember as shown in FIG. 13E. Also, various features of suchcross-sectional geometries may be combined as desired depending, forexample, on the expected loadings such an elongated member willexperience.

Referring now to FIGS. 14A and 14B, a system 700 is shown including acontroller 500 in communication with, and operably coupled to, anapparatus 701 for forming an elongated member 702 (FIG. 17A) thatexhibits a curved or arcuate portion along the length thereof. Theapparatus 701 includes a base 704 having a plurality of mandrels706A-706D located thereon. The apparatus 701 further includes a gantry708 and a carriage assembly 710 movably coupled to the gantry 708. Forexample, the gantry 708 may include one or more slides 712 which areoperably coupled with bearings (not shown) associated with the carriageassembly 710 such that the carriage assembly 710 may move relative tothe gantry 708 as indicated by directional arrow 714.

The base 704 may include a rotary table 716 configured to rotate about adefined axis 718 relative to the gantry 708 and carriage assembly 710. Amotor 720 or other actuator may be operably configured to rotate therotary table 716 relative to a supporting portion 722 of the base 704.As the rotary table 716 rotates, the carriage assembly 710, along withits associated components, may move relative to the gantry 708 (i.e., inthe direction indicated by directional arrow 714) so as to track theposition of the mandrels 706A-706D as each mandrel 706A-706Dsequentially passes therebeneath. The carriage assembly 710 may beconfigured to actively track the position of a mandrel 706A-706D passingtherebeneath such as through the use of the controller 500 and anactuator coupled to the carriage assembly 710. In another embodiment,the carriage assembly 710 may be configured to passively track theposition of a mandrel 706A-706D passing therebeneath, such as by theengagement of one or more components of a forming device 726 with themandrels 706-706D as will become apparent through subsequent discussionof such a forming device 726.

It is noted that, while the exemplary embodiment described with respectto FIG. 14 is described as including a rotary table 716 which rotatesabout a defined axis 718 relative to the gantry 708 and carriageassembly 710, other embodiments are contemplated as being utilized inconjunction with the present invention. For example, the base 704 mayinclude a nonrotating table while the carriage assembly 710 and gantry708, or similar structures, are configured to move relative to the tablesuch as by rotating about a defined axis 718.

It is also noted that the mandrels 706A-706D may not necessarily exhibita constant radius of curvature throughout their respective lengths. Itis also noted that each mandrel 706A-706D may exhibit a differentlength, radius of curvature or other geometric characteristic than anyof the other mandrels.

A material dispensing device 724 and a forming device 726 are coupledwith the carriage assembly 710. As the rotary table 716 rotates relativeto the gantry 708, the material dispensing device 724 is configured toplace one or more plies of material onto the mandrels 706A-706D. Theforming devices 726 may include a plurality of rollers 728 coupled toactuators 730 and configured to shape the plies of material placed onthe mandrels 706A-706D.

For example, referring to the schematic shown in FIG. 15A, an exemplaryoperation of the material dispensing device 724 and the forming device726 is shown. Material 740 (e.g., a ply of prepreg cloth) is fed from asupply and tension roller 742 and over a redirect roller 744 asmotivated by a pair of feed rollers 746. The material 740 passes beyonda cutting device 748 which may be used to cut the material to aspecified length, width, or both such as described hereinabove withrespect to other embodiments of the present invention. The material 740is then disposed onto a portion of a mandrel 706A by a tack roller 750.

It is noted that the tack roller 750 (and subsequent rollers encounteredby the material 740) is shown in a first elevational view with a second,rotated elevational view depicted immediately therebeneath to provideadditional understanding of how the material 740 is being shaped by theinteraction of various rollers with the material 740 and the underlyingmandrel 706A.

The forming device 726 includes a plurality of rollers 728A-728D used toshape and debulk material 740 disposed over the mandrel 706A (or overpreviously shaped material plies disposed on the mandrel 706A). Thus,for example, a first roller 728A engages the mandrel 706A to generallyconform the material 740 to the shape of the mandrel 706A. Second, a setof rollers 728B may be used to press the material against the side walls754 of the mandrel 706A. If desired, this may be accomplished withmultiple sets of rollers 728B working from the upper portion of themandrel 706A to the bottom portion as depicted in the rotatedelevational views of the rollers 728B. Another set of rollers 728C maybe used to press the material 740 into the interior lower corners 756 ofthe mandrel 706A. A squeegee 758 may be used to help pull wrinkles fromthe material at one or more intermediate locations among the rollers728A-728D. Finally a set of rollers 728D may be used to press and formthe flange members of the elongated member 702.

It is noted that the process of forming the elongated member 702includes forming, shaping and debulking the material 740 from the insideout. In other words, the tack roller 750 applies pressure to the mandrel706A and material 740 disposed thereon at the center, with subsequentrollers 728A-728D each sequentially applying pressure at a locationfurther towards the outer edges of the material 740. Such a process hasbeen determined to be efficient and effective in removing wrinkles andair gaps between laminar plies of material thereby producing a highlyconsolidated and debulked composite member.

A take-up roller 760 may be associated with the forming device 726 (orindependently coupled with the carriage assembly 710) to collect carriermaterial 762 (also referred to as backing) which may be disposed on asurface of, for example, a prepreg material used to form the elongatedmember 702. The carrier material 762, which may include a suitablepolymer material, not only keeps the prepreg material from adhering toitself when in rolled form (i.e., such as when on supply and tensionroller 742) but also may remain on the material 740 while the material740 is being shaped, formed and debulked so that the various rollers 750and 728A-728D do not stick to the material 740 or collect and build-upresin of a surface thereof. Additionally, the presence of such carriermaterial 762 may serve to protect the material 740 used to form anelongated member 702 when the various rollers 728 press and rub againstthe material 740 during forming of the elongated member 702.

Referring now to FIG. 15B, additional details are shown of the firstroller 728A, which may also be described as a scrub roller. It is notedthat while the first roller 728A of the presently described embodimentis described as a scrub roller, other or additional rollers (e.g.,728B-728D) may be configured as scrub rollers if so desired.

The scrub roller 728A may include two roller halves 800A and 800Bcoupled to a shaft 802. The shaft 802 may be coupled to the carriageassembly 710 and an actuator or other force applying mechanism (notshown in FIG. 15B) may be configured to press the scrub roller 728A ontothe mandrel 706A as indicated by the directional arrows 804. The tworoller halves 800A and 800B are configured to be axially displaced alongthe shaft 802 (i.e., along the axis 806 of the shaft 802). An actuatoror force applying mechanism 808 is associated with each roller half 800Aand 800B and configured to bias each roller half 800A and 800B towardsthe sides of side walls 754 of the mandrel 706A as indicated by thedirectional arrows 810. The force applying mechanism 808 may include,for example, a spring, a hydraulic actuator or a pneumatic actuator.

Besides the ability to tailor the amount of force being applied to theside walls 754 of the mandrel 706A, the configuration of the scrubroller 728A also enables the production of elongated members 702 thatexhibit varied cross-sectional geometries. For example, referringbriefly to FIG. 15C, an elongated member 702″ may exhibit a varyingcross sectional geometry such that the top surface, or cap 813, becomeswider as one traverses along a longitudinal axis 811 of the elongatedmember 702″. Such an elongated member 702″ might be used, for example,as a wing spar in the construction of the wing of an aircraft.

As seen in FIG. 15C, the two roller halves 800A and 800B are in a firstaxial position relative to the shaft 802 when the scrub roller 728A isat a first longitudinal position 812 with respect to the elongatedmember 702″. However, the two roller halves 800A and 800B are displacedto a second axial position relative to the shaft 802 when the scrubroller 728A is at a second longitudinal position 814 with respect to theelongated member 702″ (the scrub roller 728A being shown in dashed linesat the second longitudinal position 814). The configuration of the scrubroller 728A enables the two roller halves 800A and 800B to maintaincontact with the side walls of elongated member 702″ (and underlyingmandrel) and maintain a desired amount of force thereagainst regardlessof the change in cross-sectional geometry (e.g., the change in width ofthe cap 813).

Referring now to FIG. 15D, a schematic shows further detail of theinteraction of the scrub roller 728A with the mandrel 706A (or, moreparticularly, with material 740 disposed over the mandrel 706A). As thescrub roller 728A travels relative to the mandrel 706A in the directionindicated by the directional arrow 820, a roller half 800A (shown indashed lines for clarity) rotates about an axis 806 in the directionindicated by directional arrow 822. The roller half 800A may be shaped,contoured and positioned such that contact between the material 740 andthe mandrel 706A, as effected by the force of the scrub roller 728A, isinitiated at a desired location and is limited to a desired surfacearea. For example, as the roller half 800A rotates, it causes thematerial 740 to be initially pressed against the surface of the mandrel706A at the pressing location 824. The location of this initial pressingof material 740 against the mandrel 706A, taking in consideration therotation of the scrub roller 728A, causes the scrub roller 728A toeffectively pull the material 740 down onto the mandrel 706A. Moreover,the surface area of contact effected by the scrub roller may be limitedto a defined area 826 such as that shown with cross hatching in FIG.15D. The scrub roller 728A effectively rubs or sweeps against thematerial 740 in the defined area 826 to more effectively press and shapethe material 740 as it is pressed against the mandrel 706A. The limitedarea of contact effected by the scrub roller also prevents the scrubroller 728A from lifting the material 740 upwards and away from themandrel 706A as the scrub roller 728A continues to rotate (such as inthe area generally indicated at 828).

It is noted that the initial location of pressure or contact between thematerial 740 and the mandrel 706A effected by the scrub roller 728A maybe determined by the shape, contour, and positioning of the scrub roller728A relative to the mandrel 706A. For example, referring briefly backto FIG. 15B, the surface 830 of each roller half 800A and 800B thatcontacts the side walls 754 of the mandrel 706A (or the materialdisposed thereover), may be configured to exhibit a substantially linearsurface (as shown in plan view) or may exhibit a curved or arcuateconvex surface to further control the area and location of contact andpressure effected by the scrub roller 728A. In another exemplaryembodiment, depending for example, on the actual cross-sectionalgeometry of an elongated member 702, the scrub roller 728A may beconfigured such that each roller half 800A and 800B is coupled to anindependent shaft, and each shaft may be canted or angled relative tothe shaft axis 806 shown in either FIG. 15B or 15C in order to controlthe surface area of contact by the scrub roller 728A.

Referring now to FIG. 16A, in one exemplary embodiment, a materialdispensing device 724′ may include multiple dispensers 724A-724Cconfigured to each selectively dispense an individual ply of material740A, 740B or 740C onto a mandrel 706A. Each of the dispensers 724A-724Cmay include a supply and tension roller 742A-742C, a redirect roller744A-744C, feed rollers 746A-746C, cutting devices 748A-748C and tackrollers 750A-750C.

Each dispenser 724A-724C of the material dispensing device 724′ mayinclude a supply of material that exhibits different characteristicsthan the other supplies of material. For example, the first dispenser724A may include a ply of material 740A that exhibits a 0° fiberorientation, the second dispenser 724B may include material 740B thatexhibits a 45° fiber orientation, and the third dispenser 724C mayinclude material 740C exhibiting a fiber angle different than thatincluded in the first and second dispensers 724A and 724B. In anotherembodiment, the width or thickness of the material may vary from onedispenser to another. Another exemplary embodiment may include differenttypes of grades of material in each dispenser 724A-724C. Such aconfiguration provides considerable flexibility and efficiency in theformation of elongated members 702 that are complex assemblies ofnumerous and varying material plies. For example, if, as shown in FIG.15A, only a single material dispensing device 724 is used, material 740may have to be changed frequently on the supply and tension roller 742in order to accommodate material 740 having different fiber orientationsor other varying characteristics.

Referring briefly to FIG. 16B, another embodiment of a materialdispensing device 724″ is shown that includes a plurality of supply andtension rollers 742A-742C, each dispensing a ply of material 740A-740Cwhich passes around associated redirect rollers 744A-744C as motivatedby associated feed rollers 746A-746C. After the feed rollers 746A-746B,each of the plies of material 740A-740C may be selectively passed over acommon redirect roller 768, through a common cutting device 748 and laidupon a mandrel 706A with assistance of a common tack roller 750. Thus,through independent control of the feed rollers 746A-746C, the plies ofmaterial 740A-740C may be individually and selectively fed through thecutting device 748 and to the tack roller 750 to be laid up on amandrel. As with the embodiment described with respect to FIG. 16A, eachply of material 740A-740C may exhibit a different characteristic thanthe others, whether it be fiber orientation, material dimensions,material composition, or some other characteristic.

In other embodiments, the material dispensing device 724″ may beconfigured to dispense filler materials such as, for example, filleradhesives or small filler members known by those of ordinary skill inthe art as “noodles.” Such filler material may be utilized, for example,if an apparatus was configured to join two elongated structures formedas C-shapes in a back-to-back arrangement in order to form an I-beam. Asrecognized by those of ordinary skill in the art, such a constructionoften leaves a small recess along the edge of the joint line between thetwo members which is desirably filled with, for example, a noodle.

Similarly, the material dispensing device may be configured to lay downother materials including, for example, tackifier materials or baggingmaterials. Tackifier materials may be disposed on individual plies ofthe material 740 to enhance tack between adjacent plies. Baggingmaterials may be disposed over a mandrel 706A prior to dispensing a plyof material 740 for subsequent release of an elongated member 702 fromthe mandrel 706A. Thus, in some instances, it may be desirable to applya new layer of bagging material over the mandrel prior to manufacturinga new elongated member 702.

Referring now to FIG. 17A, an elongated member 702 is shown which may beformed through use of the apparatus described with respect to FIGS. 14A,14B and 15A-15D. The elongated member 702 is generally curved or arcuatethroughout its length. As noted hereinabove, curved or arcuate elongatedmember 702 need not exhibit a constant radius throughout its arc length.Indeed, the present invention contemplates the fabrication of elongatedmembers 702 exhibiting multiple curves and various complex geometries.Still referring to FIG. 17A, the elongated member is structured suchthat it exhibits a first radius of curvature R1 along a first edge 770of the elongated member 702 and a second radius of curvature R2 along asecond edge 772 of the elongated member 702, wherein the second radiusof curvature R2 is greater than the first radius of curvature R1. Such aconfiguration poses a particular problem in manufacturing the elongatedmember 702 since the material plies (e.g., material 740 in FIG. 15A)being dispensed from a supply and tension roller 742 exhibit generallystraight edges down each side thereof. Thus, as the material 740 isplaced on a curved mandrel 706A it tends to pucker or wrinkle along thefirst edge 770 or, more particularly, the edge that exhibits the smallerradius of curvature.

To prevent wrinkling of the material 740 (FIG. 15A) a desired amount oftension may be applied to the material 740 as it is being applied to themandrel 706A (FIG. 15A). Thus, for example, referring to FIG. 18 inconjunction with FIGS. 15 and 17A, the material dispensing device 724may be configured to apply tension to the material 740 in a directionthat is tangential to, or at a slight angle deviating from tangent withregard to the mandrel 706A at the point where the material 740 is beingplaced thereon. For example, considering the tangent line being 90°relative to a radial centerline 796 of the mandrel 706A, in oneembodiment, tension may be applied (as indicated by directional arrow774) at an angle of between approximately 89° and 91° relative to theradial centerline 796. Such tension may be applied, for example, byrestricting or otherwise controlling rotation of the supply and tensionroller 742 (FIG. 15A) as the material 740 is being dispensed therefrom.For example, a magnitude of desired resistance may be imparted to thesupply and tension roller 742 as material 740 is supplied therefrom andwhile the carriage assembly 710 and rotary table 716 move relative toone another, resulting in tension in the dispensed material 740.

Considering the use of a woven prepreg material as the ply of material740 being dispensed, application of tension to the material 740 as it isdisposed on to the mandrel 706A and subsequently shaped by the formingdevice 726 causes the material 740 to stretch along the larger radius ofcurvature (e.g., R2 in FIG. 17A) while preventing wrinkles from formingalong or adjacent the smaller curvature of radius (e.g., R1 in FIG.17A).

In other words, a tension gradient may be developed across the width ofthe material 740 as it is dispensed and formed on the mandrel 706A. Forexample, a tension gradient may be developed in the material 740 used toform the elongated member 702 such that tension is at a minimum (whichmay be nearly zero in some cases) at the lateral edge exhibiting thesmaller radius of curvature (e.g., R1) while tension is at a maximum atthe lateral edge of the material exhibiting the larger radius ofcurvature (e.g., R2). The gradient need not be strictly a lineargradient from one edge of the material 740 to the other. The weave ofthe material 740 may determine, in part, the amount of stretching thatmay be accommodated by the fabric and the magnitude of the force thatneeds to be applied to the fabric depending on the “give” of thematerial as determined by the particular weave of the fabric.

In one exemplary embodiment, a force of approximately 30 to 40 lbf(approximately 133.4 to 177.9 N) may be applied to the material 740 toplace the material in appropriate tension. Of course, the amount offorce applied to the material may depend on a number of factorsincluding, for example, the type of material being used (including theweave of the fabric), the width of the material, the radius of curvatureof the mandrel 706A, or a combination of such factors. In addition tothe tension applied to the material 740, heat may be applied to thematerial to relax the material and help facilitate the stretching of thematerial 740 along, or adjacent to, the edge exhibiting the largerradius of curvature. However, the amount and intensity of heat appliedto the material 740 may be selected and controlled so as to preventpremature curing of the material 740.

Referring now to FIGS. 19A and 19B, a system 700 including anotherembodiment of an apparatus 701′ for forming curved or arcuate elongatedmembers 702 (FIG. 17B) is shown. The apparatus 701′ is similar to thatshown and described with respect to FIGS. 14A and 14B with a fewmodifications. Generally, the apparatus 701′ includes a base 704 havinga mandrel 706′ located thereon. The apparatus 701′ further includes agantry 708 and a carriage assembly 710 movably coupled thereto. The base704 may include a rotary table 716 configured to rotate about a definedaxis 718 relative to the gantry 708 and carriage assembly 710. A motor720 or other actuator may be operably configured to rotate the rotarytable 716 relative to a supporting portion 722 of the base 704.

A material dispensing device 724′ and a forming device 726′ are coupledwith the carriage assembly 710. As the rotary table 716 rotates aboutthe defined axis 718 relative to the gantry 708, the material dispensingdevice 724′ is configured to place one or more plies of material ontothe mandrel 706′. The forming device 726′ may include a plurality ofrollers 728 coupled to actuators 730 and configured to shape the pliesof material placed on the mandrel 706′. The mandrel 706′ is coupled tothe rotary table 716 in a spaced relationship thereto by a plurality ofsupport structures 780. The material dispensing device 724′ and theforming device 726′ are positioned radially inwardly of the mandrel 706′and configured to engage and interact with the mandrel 706′ as itrotates along with the rotary table 716. The configuration andorientation of the material dispensing device 724′ and the formingdevice 726′ may be referred to as being parallel to the rotary table 716whereas the configuration and orientation of the material dispensingdevice 724′ and forming device 726′ shown in FIGS. 14A and 14B may bereferred to as being normal to the rotary table 716.

Referring to FIG. 17B, a portion of an exemplary elongated member 702′is shown which may be formed using the apparatus 701′ shown anddescribed with respect to FIGS. 19A and 1-9B. The elongated member 702′is generally arcuate or curved such that a first surface or edge 782exhibits a first radius of curvature R1′, a second edge or surface 784exhibits a second radius of curvature R2′, the second radius ofcurvature R2′ being greater than the first radius of curvature R1′. Aswith previously described embodiments, a force may be applied to anymaterial disposed on the mandrel 706′ to induce a tension gradient andprevent wrinkling of material at or adjacent the smaller radius ofcurvature (e.g., R1′).

It is noted that the cross-sectional geometry of the elongated member702′ is rotated along a general radius of curvature 786 relative to thatof the elongated member 702 shown in FIG. 17A. It is again noted thatthe curved elongated member 702′ need not exhibit a constant radius ofcurvature. The ability to produce elongated members 702 and 702′ of suchvaried configurations enables production of highly customized andcomplex structures with relative ease and efficiency.

Referring now to FIG. 20, a cross-sectional view is shown of anexemplary elongated member 702″ formed in accordance with another aspectof the present invention. The elongated member 702″ comprises a firstmaterial ply 788, which extends from a first edge 770 of the elongatedmember 702″ through about half of the “width” or cross-sectional extentthereof, and a second material ply 790 which abuts the first materialply 788 and extends to the second edge 772 of the elongated member 702″.A third ply 792 is disposed on top of the first and second plies 788 and790 in a laminar manner and forms a bridge over the abutment joint 794of such plies. Additional plies may be disposed over the first, secondand third plies 788, 790 and 792 in a repeating pattern (or in someother defined pattern) if so desired.

The use of multiple adjacent and abutting plies of material reinforcedby laminar “bridge” plies provides additional flexibility in forming acurved elongated member 702″. For example, if the radius of curvature ofthe elongated member 702″ is such that use of a single ply of materialto form the entire cross-sectional geometry would not be feasible,either because wrinkles would still develop or because the amount oftension required to avoid wrinkles would be detrimental to the strengthcharacteristics of the material, separate plies of narrower width may beused. In other words, the tension required to stretch a material plythat is wide enough to extend between the first radius of curvature R1and the second radius of curvature R2 is greater than that required tostretch a material ply that is wide enough to extend between, forexample, the second radius of curvature R2 and a third radius ofcurvature R3. Thus, using multiple laterally adjacent plies of materialenables the construction of elongated members 702″ exhibiting “wider”cross-sectional geometries while reducing the tension applied to, andthe stretching experienced by, the material plies.

It is noted that other variations of the present invention are alsocontemplated. For example, while the exemplary embodiments have beendescribed to include a mandrel and a plurality of complementary rollers,two sets of complementary rollers—an upper set, and a lower set—may beused to form the elongated members. Thus, for example, a plurality offibers may be passed through an upper female set of rollers and a lowermale set of rollers to obtain a desired cross-sectional geometry.However, it is noted that the use of a mandrel, such as in the abovedescribed exemplary embodiments, may provide more precise placement ofthe plies and control of fiber orientation. Additionally, while variousembodiments have been described in terms of utilizing carriageassemblies and gantries, it is further contemplated that robotic armsmay be utilized in positioning the rollers and applying appropriateforce or pressure to materials disposed over a mandrel. Such a robot maybe configured such that the associated roller or rollers arepositionable about multiple axes.

Additionally, various materials may be used in forming the elongatedstructural members. For example, composite tape, fabric, dry fabric orvarious combinations thereof may be used. Furthermore, filler materialsmay be introduced into the elongated structural member as deemedappropriate. Such filler materials may include, for example, foam,metallic or other nonplastic materials.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the inventionincludes all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

1. A method of forming an elongated composite structural member, themethod comprising: providing a substantially elongated mandrel having anexterior surface exhibiting desired geometry the elongated mandrelfurther exhibiting an arcuate portion along at least one section of alength thereof; laying up a first ply of preimpregnated fiber reinforcedmaterial over the mandrel; applying a force to the first ply toestablish a desired amount of tension within the first ply, whereinapplying a force to the first ply to establish a desired amount oftension within the first ply includes applying a force in a directionthat is substantially tangent to a radius of curvature of the mandrel ata location where the first ply is being laid up on the mandrel; andpressing the first ply onto the mandrel in a conformal manner includingpassing at least one roller over the mandrel and the first ply whilemaintaining the desired amount of tension within the first ply, the atleast one roller being at least partially complementary in shape withthe mandrel.
 2. The method according to claim 1, further comprisinglaying up a second ply of material over the first ply of material,applying a force to the second ply to establish a desired amount oftension within the second ply, and pressing the second ply onto thefirst ply in a conformal manner with the at least one roller whilemaintaining the desired amount of tension within the second ply.
 3. Themethod according to claim 2, wherein pressing the second ply onto thefirst ply includes consolidating both the first ply and the second ply.4. The method according to claim 3, further comprising maintaining thefirst ply and the second ply in a substantially uncured state.
 5. Themethod according to claim 2, wherein laying up a first ply ofpreimpregnated fiber material over the mandrel includes defining thefirst ply to exhibit a first fiber orientation and wherein laying up asecond ply of material over the first ply of material includes definingthe second ply of material to exhibit a second fiber orientationdifferent from the first fiber orientation.
 6. The method according toclaim 2, wherein laying up a first ply of preimpregnated fiber materialover the mandrel includes defining the first ply to exhibit a firstwidth and wherein laying up a second ply of material over the first plyof material includes defining the second ply of material to exhibit asecond width different from the first width.
 7. The method according toclaim 1, wherein passing the at least one roller over the mandrel andthe first ply includes sequentially passing a plurality of rollers overthe mandrel and the first ply.
 8. The method according to claim 7,further comprising configuring the plurality of rollers such that afirst roller partially complementarily engages the mandrel over a firstsurface area of the mandrel and such that a second rollercomplementarily engages the mandrel over a second surface area of themandrel.
 9. The method according to claim 1, wherein applying a force tothe first ply to establish a desired amount of tension within the firstply includes stretching a portion of the first ply along an areaadjacent a first lateral edge of the first ply.
 10. The method accordingto claim 9, wherein applying a force to the first ply to establish adesired amount of tension within the first ply includes preventingwrinkles from forming in the first ply along an area adjacent a second,opposing lateral edge of the first ply.
 11. The method according toclaim 9, further comprising applying a desired amount of heat to atleast an area of the first ply adjacent the first lateral edge.
 12. Amethod of forming an elongated composite structural member: providing asubstantially elongated mandrel having an exterior surface exhibitingdesired geometry, the elongated mandrel further exhibiting an arcuateportion along at least one section of a length thereof; laying up afirst ply of preimpregnated fiber reinforced material over the mandrel;applying a force to the first ply to establish a desired amount oftension within the first ply, wherein applying a force to the first plyto establish a desired amount of tension within the first ply includesapplying a force in a direction that is approximately 89° to 91°relative to a radial centerline passing through the arcuate portion; andpressing the first ply onto the mandrel in a conformal manner includingpassing at least one roller over the mandrel and the first ply whilemaintaining the desired amount of tension within the first ply, the atleast one roller being at least partially complementary in shape withthe mandrel.
 13. A method of forming an elongated composite structuralmember, the method comprising: providing a substantially elongatedmandrel having an exterior surface exhibiting desired geometry; couplingthe mandrel to a rotary table; laying up a first ply of preimpregnatedfiber reinforced material over the mandrel; applying a force to thefirst ply to establish a desired amount of tension within the first ply,pressing the first ply onto the mandrel in a conformal manner includingpassing at least one roller over the mandrel and the first ply whilemaintaining the desired amount of tension within the first ply, the atleast one roller being at least partially complementary in shape withthe mandrel; and coupling the at least one roller to a carriageassembly, and wherein passing the at least one roller over the mandreland the first ply includes rotating the rotary table and the mandrelbeneath the carriage assembly.
 14. The method according to claim 13,further comprising tracking the mandrel with the carriage assembly whilethe rotary table rotates including displacing the carriage assembly in aradial direction relative to the rotary table.
 15. The method accordingto claim 1, further comprising forming the elongated compositestructural member to substantially exhibit a cross-sectional geometry ofa hat as taken transverse to a length of the elongated member.
 16. Themethod according to claim 1, further comprising forming the elongatedcomposite structural member to substantially exhibit a cross-sectionalgeometry of at least one C-shape as taken transverse to a length of theelongated member.
 17. The method according to claim 1, furthercomprising forming the elongated composite structural member tosubstantially exhibit a cross-sectional geometry of at least one angleas taken transverse to a length of the elongated member.
 18. The methodaccording to claim 1, wherein laying up a first ply of preimpregnatedfiber reinforced material includes laying up a first ply of fiberreinforced material impregnated with a thermosetting resin.
 19. Themethod of claim 1, further comprising forming the elongated compositestructure member to substantially exhibit an asymmetrical geometry. 20.The method of claim 1, further comprising forming the elongatedcomposite structure member to have a cross-sectional geometry thatvaries along a length of the elongated member.
 21. The method of claim1, wherein laying up the one ply of preimpregnated fiber reinforcedmaterial over the mandrel further comprises: laying up the one ply ofpre impregnated fiber having a flexible backing.
 22. The method of claim21, further comprising: removing the flexible backing after the firstply has been pressed onto the mandrel.
 23. The method of claim 21,wherein the flexible backing is a polymer backing.
 24. A method offorming an asymmetric elongated composite structural member, the methodcomprising: providing a substantially elongated curved mandrel having anexterior surface exhibiting a desired asymmetrical geometry and a variedcross-sectional shape along a length of the elongated curved mandrel;laying up at least one ply of preimpregnated fiber reinforced materialon the mandrel; applying a force to the at least one ply to establish adesired amount of tension within the first ply, wherein applying a forceto the first ply to establish a desired amount of tension within thefirst ply includes applying a force in a direction that is substantiallytangent to a radius of curvature of the mandrel at a location where thefirst ply is being laid up on the mandrel; and pressing the at least oneply onto the mandrel in a conformal manner including passing at leastone roller over the mandrel and the at least one ply while maintainingthe desired amount of tension within the at least one ply, the at leastone roller being at least partially complementary in shape with themandrel.
 25. The method of claim 24, wherein laying up the at least oneply of preimpregnated fiber reinforced material of the mandrel furthercomprises: laying up the at least one ply of preimpregnated fiber havinga flexible backing.
 26. The method of claim 25, further comprising:removing the flexible backing after the first ply has been pressed ontothe mandrel.
 27. The method of claim 25, wherein the flexible backing isa polymer backing.